The World’s Safest Business (Feb, 1957)

AMATEUR rocketry is on the upswing in the United States. Many boys are building rockets today who would have been plane model fans a generation back. By rough count, there are approximately 100 amateur rocket societies in the U. S.—and no one knows how many young men building rockets.

When we get letters from amateur rocket men—most of them asking for detailed, specific information—we usually give three loud cheers and shake in our boots at the same time. It’s nice to know that there are people who are, unlike ourselves, interested in rockets not as a means of buying groceries and shoes for Junior.

But we shake in our boots because we know rocket flight testing is dangerous.

Professional rocketry today can truly be called the world’s safest business. In the 11 years of White Sands history, we have fired over 10,000 rockets and lost only two men—men who would still be with us if the rules had been followed. Working on the proving ground with highly toxic propellants, missiles going wild and explosions of bad rockets, we are actually safer than when driving to and from work. We follow the rules. If you are going to build and fly rockets, you must accept the responsibility which goes with it.

You must be willing to abide strictly by these rules of safety:
1. Rockets are high explosive devices, all of them. Treat them with great respect and caution at all times.

2. Do not expose rockets to heat over 125° F, or to shock of handling or dropping. Heat can ignite propellants. Shocks can crack solid propellant grains, exposing more burning area and so increasing burning rates and pressures inside rockets. Shocks can also damage any delicate devices in a rocket, misalign the rocket fins or structure, or actually crack vital parts or subject them to too much strain.

3. When mixing solid propellants, do so by diluting them with water and wear a shatterproof face shield. When working with liquid propellants, check with the manufacturer or a chemistry teacher to learn what protection you should have against their toxic effects.

4. When you fire a rocket, do so by electrical means. Keep the firing leads shorted or grounded both at the rocket and at the firing switch until the last possible moment. Make certain your are at a safe distance in case of an explosion. Do not use blasting caps for anything! Use a length of nichrome wire to heat up a small bit of black powder to give you a puff ball of flame for ignition. If you have a misfire with a rocket, put all safeties back on at once and do not approach the missile for at least an hour.

5. When you fire a rocket, do it far away from any building or inhabited area. Before shooting, obtain permission from the owner of the land to do so. Don’t fire in a wind, and always fire in a safe direction; “up” is not safe, so shoot at a slight angle at least.

6. Obtain the help and advice of somebody in your area who knows something about chemistry, physics, explosives, or science in general. Don’t go blundering by yourself. You won’t have trouble getting help for rockets are exciting devices! •

@Jari – The RepRap is almost there (price and likely material-cost are in the ballpark, but not feature-size – also, that would only be if you don’t have something better to do with your time – most people who build such machines build them for the fun or knowledge of it) – current models are Darwin (v1) and Mendel (v2):

The nice thing about RepRap is that you can bootstrap to the next level with each revision (how do you suppose humans went from banging sticks and stones together, to fabricating computers? A long, slow process of technology bootstrapping, that’s how).

Another possibility is repurposing a Cricut to cut slices from thick paper for a layered/stacked 3D model; there’s probably ways of automating this process.

Much of what you want is possible to a certain extent for the price point, if you’re willing to do some DIY. You wouldn’t believe the things some people have done completely homebrew (and generally open source) – for example:

Unfortunately those kind of printers produce stripy finish, which won’t do for making “mothers” for a silicon molds of scale model parts. Other option would be a small CNC-mill, but those are noisy, “dirty” and needs several milling bits for making one piece.

But while thinking back how printers have evolved from, say mid-80’s, I’m sure there is a desktop 3D machine for my needs in 10 years or so.

Harry Stine! G. Harry Stine was a pulp SF writer who often talked about his model-rocket days in Analog Magazine. He is best known for “Shuttle Down”, a novel about an emergency landing of the Shuttle on Easter Island. Before launches were cancelled permanently from Vandenberg in CA following Challenger, NASA actually used his novel in the planning process, since shuttles launched from there would be high-inclination and (in some orbits), pass over la isla de Pascua.

@Jari – I certainly agree with you there; they aren’t accurate enough yet at the DIY level to make intricate parts – however, the thing about the RepRap (at least) is that it is accurate enough to bootstrap itself to the next level of accuracy. From what I have gathered (because I don’t have the time or need for such a machine – yet), when you want to make a RepRap, you try to find someone who already has one that can produce the plastic components you need to assemble the rest of the machine. You then gather the remaining components and build it – and hopefully you can pass on more parts to other builders in the future. The ultimate goal being, of course, a machine that can fully replicate itself (a noble goal, but one that has yet to be achieved outside biology). I’m not even sure a commercial machine can meet your requirements, actually – most of the models I have seen from such machines don’t seem to have the smooth finish you are looking for. Of course, one could use such a machine (or a DIY machine) to build a model that could be finished by another machine or process to the accuracy/smoothness desired, I suppose…

Jari says: April 30, 20112:48 pm

Andrew: As you said, the ultimate goal that reprap is trying to achieve is a noble one. There are commercially available machines, that produce a finish with an accuracy I’m looking for. They work using laser to cure liquid polymer instead of depositing molten plastic from layer to layer. But the price is way too steep for me, being well over 30000$……